The present invention relates to devices for controlling an amount of light which is allowed to come through an opening such as a window or glass door, and more particularly concerns a venetian blind for partially covering such an opening and thereby controlling the amount of light passing through the opening.
Many devices have been proposed in the prior art for controlling the amount of light coming through an opening, and include many varieties of venetian blinds which incorporate means to vary the size of the area of the opening over which said blinds have control. Examples of such devices can be found in the following U.S. Pat. Nos. 2,914,122 and 2,994,370 by Pinto; U.S. Pat. No. 4,200,135 by Hennequin; U.S. Pat. No. 4,377,194 by Tsuhako; U.S. Pat. No. 4,484,612 by Vechiarelli; U.S. Pat. No. 4,572,267 by Stein et al.; and U.S. Pat. No. 4,768,576 by Anderson; U.S. Pat. No. 4,788,188 by Blytheway, Jr.; and U.S. Pat. No. 4,955,248 by Lindstrom. While these and other examples of venetian blind devices of the prior art may be suitable for a particular purpose to which they address, it will be apparent to those skilled in the art that said devices would not be as suitable for the purposes of the present invention, which include providing means to control separately the amount of light passing through different regions of an opening. An example of a situation in which a need for this type device exists, is when an individual desires to block a substantial amount of light passing through a lower region of a window for privacy, while simultaneously desiring a significantly greater amount of light to pass through an upper region of the window for either viewing through said upper region or for illuminating an area behind the window.